Always worth reading the tech data sheet for paints, which are usually online. The U-POL etch primer TDS states it has a 2 year shelf life. Some etch primer formulations are stable and some react with themselves after a while and form 'lumps'. It seems U-POL is one of the latter.tom_tom_go wrote: โTue Oct 23, 2018 7:28 pm 1) U-POL etch primer sprayed clumpy despite being brought up to room temperature and shaken well.
2) Halfords clear matt lacquer produced white bits on the paintwork when sprayed so has it expired as well as it is also a few years old and stored in the same garage.
Matt clear finishes have a matting agent added which is a fine powder, talc is a common one. Left for a long time the fine particles clump together and settle out as a hard layer. When you shake the can the layer breaks up into little white bits which don't fully disperse again. You'd probably get RSI from shaking the can, before you could completely dispersed all the clumped particles again.
Note water vapour can get into an aerosol, although it isn't the cause of Tom's problems. The steel can may be impervious, but the valve parts are plastic and water vapour can diffuse slowly through most plastics, as can gases and some solvent vapours, for that matter.
Regards,
Graeme
.